Grinding machine



Feb. 19, 11935. F, J. THELER 1,991,712

GRINDING MACHINE Filed Feb. 29,' 1932 4 Sheets-Sheet 1 S5577/ f ff Feb.. 19, 1935. F J. THELER 1,991,712

GRINDING MACHINE I Filed Feb. 29, 1932 4 Sheets-Sheet 2 i Mm Gttorneg Feb. 19, 1935.

F. J. THELER GRINDING MACHINE Filed Feb. 29, 1952 4 Sheets-Sheet 5 Feb. 19, 1935.

F. .1.A THELER GRINDING MACHINE Filed Feb. 29, 1932 4 Sheets-Shea?l 4 'Ir/gg Patented Feb. 19, 1935y UNITED STATES 1,991,712 g y Y GRINDINGMACHINE Frederick J. Theler, Cincinnati, Ohio, assigner to Cincinnati Grinders Incorporated, Cincinnati, Ohio, a corporation of Ohio. f

o Appxicationrbrgary 29, 1932,1seria1No. 595,752

1v claims. (0151-108) This invention relates to improvements in machine tools and especially to improvements in grinding machines. Y Y f The deviceof this invention has particular utilv-f, ity `for grinding comparatively thin cylindrical Varticles such .as sleeves made of cork 'or other soft material as used inthe textile industryY for guiding thread `to the weaving machines.Vv vIt is to ,be understood, however, Ythat the invention is `i not restricted solely yto that type of article, but

ernay be employed with equal facility for grinding other ysleeves-that have a wall thickness which is to beV held within comparatively narrow limits. ,The invention being particularly directed to' the i means for positioning the work on carrying spindles and for ejecting the work from such spindles.

Therefore,one of the principal objects of the `present invention is thefprovision yof improved loading and ejecting lmechanism` for Vuse, with machine tools for positioning the work relative to the carrying spindle or arbor and for ejecting said work from the spindle or arbor. 4 Another object of the invention is the provision of improved work carrying mechanism for supporting the work and presenting same to a grinding wheel' to effect a stock removal therefrom.

A further object ofv the invention, is the provision of improved means for effecting the rotation of sleeve-like work pieces. Y

Other objects and advantages of the present invention should be readily-apparentby reference to the following specication considered in con- 4junction with the accompanying drawings forming apart thereof and it is to be understood that 5 any modications may "be made in the exact structural details there shown and described withinthe scope oi the appended claims without departing fromor exceeding the spirit of the invention.

In the drawings: v l

Figure 1 is a front elevation of a'grinding machine embodying the improvements of this invention. Y

yFigure A2 is Va top plan view of the machine shown in Figure 1.v e l f Figure 3 is a'fragmentary sectional view as seen substantially from line 3-3 of Figure 1.

Figure 4 is a view partlyv in section and'partlyV Figure 6 is an elevational View of certain partsv shown-.in Figure 4 and as seen particularly from 55 1m@` 67-6 of Figure 4. v

Figure 7` is a fragmentary sectional view as seen ysubstantially from line7--7 of Figure 3. Y -f Figure 8isa sectional view taken on line 8-8 of Figure 4.- 1

Figure 9 is a sectional view taken-on line 9-9 of 5 Figure4. e, e

Throughoutrthe several views of therdrawings Asimilar reference characters are employed-to de-K,

note the s ame or similar parts. l

VA machine embodying this invention may comprise a bed 10 having rising AYtherefrom at one end thereof a pedestal bearing 11 in whichis journaled a spindle 12 having securedto its one end a grinding wheel 1,3. The grinding wheel and spindle are adapted to be rotated at a high grinding 15 rate of speed'inva clockwise direction asindicated bythe arrowassociated with the grinding wheel housing; The Vbed' 10 is furtherprovided onits fupper surfacewith a guideway 14 for a lower slide 15 for guiding saidslide in its movement toward and from the grinding wheel. 1 'Ihe said lower slide l5 is inturn provided with a guideway 16 for the upper slide 17 which vhas associated therewith a `rotation controllingv rate of'speed. Any usual or 30 suitable driving lmeans maybe employed for rotating both the grinding wheel and the'friction kdrive wheel andthe said wheels have their proximate points spaced from one another an ,amount equal to the desired finished Ysize of the `work piecesto be operated upon and form agrinding .throat between them.

'Ihe lower slide 15 has secured to it at its inner end a bracket .or journal bearing 22 having formed therein an enlarged bore or opening 23 carrying a liner or bushing 24. Journaledfin theYV liner or bushing 24 isa bearing portion 25 of a plate 26. The plate 26 is provided centrally thereof with an enlarged opening.27,; through which the friction drive wheel spindle projects.

, Theplate 26 has secured toits rear face a ring 28 by ,means of cap` screws or the like 29; The

-ring 28 has fastened to itin a circular path concentric with the plate 26 a-plurality of spindles or i arbors 30. The said arbors each havinga reducedend 31 which' extends into the ring 28 being secured .therein between a shoulder 32 'formed on the arbors and a nutV 33 threaded on the extreme end thereof. Each of the arborsextend through an aligned .bore in theV plate 26 against which the shoulder 30 contacts and is provided at its outer or free end with a substantial point 34 to facilitate insertion of the work thereon.

The spindle housing or head 19 has its outer end enlarged to form a hood portion 35 which encloses the plate 26 and mechanism carried thereby and the friction drive wheel 21. Mounted on the upper end of thehood 35 is-a prime mover or motor36 being geared or belted by a flexible transmission member 37 to a pulley 38 on one end of a worm shaft 39. The worm shaft 39'is journaled in a bracket 40 secured to the journal bearing 2 2. The worm shaft 39 has integral therewith or secured theretoa Worin. 41 meshing with a worm wheel 42' on oneA end of a driven shaft 43 journaled in anti-friction bearings-carried by the bracket 40 and the journal bearing 22. The shaft 43 has secured to it Vor'o'rmed integral therewith a worm 44 meshingwith worm teeth 45 formed around the outer ysurface of the bearing portion25 of the plate 26 and whereby the said plate isdriven `at a very slow" rate of Speed-for actuatingfthe arbors circumferentially of the friction drive wheel 21. The plate 26fis heid againstinaxivertent' disassociation lwith the journal bearing 22 by a clamp plate 46-forming l'theilan'gethat extendsbeyond the periphery of Vthe bearing25 and-isseated in arecess 47 formed in the rear face of' the '-'journal bearing 22', the

vAs was suggested' abovathe carrierpiate 26 is Vactuated ata very-slowrate of speed?circumfer-V entially of the frictionv "drive wheel -for passing Vvthe worlk insuccession throughV the grinding .throat-while presenting saidwork'pieces 49 to 'the action vof the grinding wheel. The diameter o the1arbors Ellis substantially equal to the bore within theY work v'pieces sov that Vconsiderablev pressure may be necessary to properly slide the dii ` :sleeve like workpieces onto-the arbors which is somewhat' diiicult' withVv the said arbors constantly moving.- For-this vreason positively actuated mechanical means-areprovidedtor sliding the work onto the `arbore and abutting same against the shoulderBZorinedlthereon and prop- `-erlyfpositioning the said work relative-to the ar- Abo'rs andi wheels.' This positive vrr-ieailiscomprises Aor otherwise securedy a shaft 57.A The shafts 53; and 57- are iournaledina bracket or housing 58 while the shaft 52 is mountedf'ina supplementaihnusing-s.' Y

.Extending through the housingB-and supplementalihousing 59'is .a sleeve 60 whereby the said parts are substantially connected. to form a` unitary, structure :enclosing the friction loading yrollers orwheels 559mm '51,.'driven gears 52 and i :mdy 'the common :drivingr'gear '56 :as well as providing y:suitable journalstor the shafts` The sleeve dwhich connects the housing portions 58 and 59`rsurrounds the Vdrivingshaft 57 and forms a pivotalE connection. for said' housings wherebyV 'the positionfof rollerspr Wheels 5i) and 51 may' bezcireurnerentially. adjnstedwith respect tmone another as well as whereby the position of the. roller or' wheel 5G may' be varied vas respects the axis pf thearbors vpassing there under so thatfdifterent sizes Dt. Work .pieces be acnom-modated thereby; dnzordier'ito :adjust the Theshaft 57 is provided intermediate A with a gear 72, see Figures 4 and 8, Ymeshingwith relative position of the roller or wheel51 the shaft 57 is vertically raised'or oscillated about a. point later to be described by means of the bolt 61 which has a pivotal connection at 62 with the shaft 57 and a threaded end 63 passing through an enlarged perforation 64 formed in the upper wall of the hood 35.

Lock nuts 65 are provided for ylocking the bolt 61 in its several adjusted positions.

The other end ofthe shaft 57 is journaledin `bearing portion 66 of arm 68, see Figure 8, the. arm 6,8 having at its other en'd the bearing por--y cured inthe sleeve-like portion 71'of bracketV f member. 40. By this construction as notedaloof/e1v Y the shaft 5'7 is oscillated about Ytheaxis of the f sleevej'O and thereby alters the position of the circumference of friction rollers or wheels 50 and 51 as respects the axisof the arbors" 30.

a pinion 'T3 loosely journaled on Ya stud 741c'arried by the arm 68 so thata driving connection yis maintained between gears 72 and 73Yregard1fe'ss its ends" of the'adjustment of the shaftl 57. 'l'hege'at-e'm is further provided with' a Vreduced portion '1 ';-n``

which'is keyed or otherwise secured 'arpilleyfmf 1 the like 76'ior the belt or otherrtransmisslonf member 77.- This belt 177 is in turn extended* about a pulley or they like 78 mounted-Tin alignment therewith and securedto tliedx'ivng shaftVA-` l 48, the belt passing through-a cored opening` pinion 80 meshing withl a complementary bevel` rpinion-181 keyed or otherwise secured to the end of a shaft 82 which is journaled inthe sleeve 70 i carried by the bracket 40 above described. The shaft 82 is held against .inadvertent disassociation with the sleeve Z0 by means of a 'collar 83 secured to the rear Vend of the shaft 'and abutting the end of the sleeve 79 and sleeve-like.

bearing portion 7l. This shaft `82 f has further secured to it abevel gear 84 meshing*with'a crunplementarybevelgear 85 secured .tothefupper'end o'fal verticallydisposed shaft 86. shaft extends verticallyy of the-machineg and passes 1 through housing sectionsV 87l and `8"8.v vhich are :similar in vlconstruction' .to tlfiel'iousing sections 58 and 59l above described. "The vertical shaft'A 86 drives a gear 89with'in the housingST- kwhich* initurn drives a pair of friction rollers vor Y wheels 90 and 191 similarfin all respects'to the rollers or wheels 50 and 51 above described but rotated in a direction opposite to that in which thewheels 50 and 5l'. are driven.- VThese"rollers 90 and 91 are adapted toeject or strip the-work pieces from the spindles or arbors() of actuating :the Y'said `work' pieces toward. thecarri-erpiate 26as do .the rollers orwheels 50 and-511".

The shaft 86 is adapted to be adjusted 5to-saryY the relativ-epositions between the rollersQO and V91 and the arbors 30 in the same manner-that@ :shaft 571s adjusted for whichpurpose ithas v pivoted at 92 abolt v93 extending throughm eiongated perforation 94 formed in .a portion' of 'the hood 35. In order .to-maintain' a proper connection between the bevel gears 84 andi 85mming the adjustment of the housing 87S8 the upper end ofV the vertical shait is .oumald-ima 'bearing portion 95 of Va righi; angle arm' 96. 'nils l lgear 85 to roll aroundv the axis ofzthe the aXis ofthe bearing portion 95..` The second bearing portion 97 is journaled-onthe sleeve '70 so that adjustment 'of the housing 87-88 toward andfrom the'spindles o r arbors 30 `will cause the sleeve 70 on thepitch circleof the gear 84.

As is well known the grinding wheel 13 is sub- `ject to wear which would cause an-opening up of the'grinding throat thereby destroying the size vthereof and resulting in producing work pieces-of -a larger size than desired and to obviate this, the

parts are adapted to be` adjusted relative to one another. For this reason there is provided an adjusting screw' 98 having its. threaded A'end threadedly received by a nut 199 carried byv the rear wall of the bracketl. The other end of this screw is journaledin a bracket 100 secured to an extending portion 101 of theA bed 10. A pilot for hand wheel 102 is secured to the screw98Y be- Vyo'ndthe bracket 100 for rotating thesaid screw.

" The operation of the mechanism is as follows:

By reference to Figure 1, it will be noted! that '.arbors`103a,v 10317, and103c` are without workpieces and it is while the arbors are passing throughthis Zone that oneend of a work piece is placed onthe arbor.` It is only necessary that the end of the work be forcedf onto the 'arbor a distance sui'licient to pass under the foremost of the rollers 50 and 51. These rollers are rotated in a clockwise directionas seen in Figure 3 and while Vthe plateis moving underthe roller the frictional contact between the work and the roller will cause vthe work tobe axially shifted along the arbor toward the seating collar 32. If the work is not fully seated bythe foremost roller 50 it will in passing theroller A51`be again-acted upon for iirmlysreating the rearmost end of the work against 'the'seating' shoulder 32.' The carrier plateis-continuously rotating and passing successive workV pieces down between the grinding wheel and friction drive wheel. Prior to engagement of the work with the grinding wheel the friction drive-wheel engages and rotates. the work at the desired speedy This `rotation ofthe work continues vuntil the work passes 'throughthe grinding throat and eventually leaves contact with the friction drive Wheel. -As thefinishedy work reaches the housing 87'-88 the friction rollersv 91 and'90 respectively rotatingiin acounterclockwise direction, as seenin Figure 6, engage therewith and shift it relative to the arbors in `a direction opposite to that in which the work was `shifted by the rollers 50 and 51 or in'other words, strip successive Workpieces from` their respective arbors causing same to fall by gravity into a It'Y should also be noted'that'the housing sec-V tionsv 58 and 59 are'clamped or locked in ,position, after they have been adjusted for holding the rollers vor disks in adjusted positions, by meansof a locking screw or bolt 106 extending through the arcuate slotY 107, formed in thehousing 59, into the housing 58. The housing sections 8'7 and 88 are similarly secured to oneanother. Y

`What is claimed'is: .n

1. In a grinding machine of the class described,

`the combination of'a grinding wheel; a friction drive wheel opposed tothe grinding wheel-and spaced therefrom, a rotatable .work carrying member supporting a plurality of work piecesfr passing same through. the grinding throat Vformed f between the grinding wheel andfrictiondrive Wheel, Yarborsl carried bythe rotatable fmemb'er individually receiving the work pieces, means for positioning the work on the arbors, and additional 'means forejecting `the workfrom the arbors, said positioning and ejecting means each comprising friction rollers spaced from the arbors a4 distance equal to the thickness of thework and engaging the work between themselves and the .arbore 2. In a vgrinding machine for grinding the exterior surface of cylindrical sleeves and the like the combination of agrinding wheelrotatable at a high grinding frate'of speed, an opposed friction drive wheel spaced from the grinding Ywheel a distance equal to'the final .size .of the workl and forming `a grindingfthroatthereby, a rotatable workcarrying plate adjacent the friction drive wheel, arbors projecting yfrom fthe work carrying platein circumscribing relation `to the` friction drive wheel, the friction drive wheel and arbore' being; rotatable at slower speeds than the grinding. wheel and about axes eccentric toone another whereby work pieces carried by the arbors are brought into simultaneous engagement with the grinding wheel and friction drive wlieelwhen within the grindingfthroat, means for rotating the work carrying plate ata slower `speed than the'frotationlof Vthe friction drive wheel, means disposed. radially of the friction drive wheel andr `werk `carrying plate for positive engagement with .the work for actuating same relative to the arbors `and* positioning th-e work thereon,` and means for positively actuating said work. positioning means. V3. In a grinding machine for grinding the exterior surface of cylindricaljsleeves and the like the combination of a grindingwheel rotatable at a `high grinding rate of,` speed, an opposed friction drive wheel spaced from the grinding wheel a distance equal to the nal size of the workand forming'a grinding throat thereby, a rotatable work carrying plate adjacent the friction drive wheel, arbors projecting from the work carrying plate. `in circumscribingv relationto thevfriction drivewheeL the friction drive wheel andarbors -being rotatable at slowerspeeds than the grinding wheel and about axes eccentricto one another whereby work pieces carried by the arbors are broughtV into simultaneousengagement with l the grinding wheel and friction drivewheel when within the grinding throat, means for rotating the work carrying plate at a slower speed than thek rotation of the friction drive wheel, means disposed radially of the friction drive wheel and work carrying plate for positive engagement with 'the work foractuating same-relative to thearbors and positioning the work'thereon, means for positively actuating said work positioning means; and additional means extending radially of the friction drive wheel and work carrying plate for ejecting the Vwork from the arbor at the conclusion of the grinding operation.`

4. Ina grinding machine for grinding the exterior surface of cylindrical sleevesand .the-like the combination of a grinding wheel rotatable at a high grinding rate ofspeed,` an opposed friction drive wheel spaced from the grinding wheel a distance equal'to the nal size ofthe work and forming a grinding throat thereby, a rotatable feo work carryingl plateadjacent the friction drive wheel, arbors projecting from the work carrying 4plate in -circumscribi-ng `Irelation to the friction jdrive wheel, thebfriction drive wheel and arbors ebeing rotatable `at slower speeds than the `grinding .,wheel'and about axes eccentric to one another Awhereby work pieces carried by the arbors .are `:brought into simultaneous engagement with Ythe ,grinding -wheel and friction drive wheel when lwithin the grinding throat, means for rotating the lwork; carrying plate at a slower yspeed than =the rotation of the friction drive wheel, means disposed .radially` of the friction drive wheel vand work carrying plate for positive engagement with .the .adjacent'surface ofthe arbors, and means for .adjusting the position of the rollers relative tothe arbors to enable different sizes .of `work piecesto be ground. n 5'. In a grinding machine for grindingthe ex terior surfaceof cylindrical sleeves .and the like v the combination of a grinding wheel rotatable at a high grinding rate .of speed, an opposed friction drive wheel Vspaced from the grinding wheel va distance equal tothe final sizeof thework and forming. Ya grinding throat thereby, .a rotatable work carrying plate adjacent the friction drive "wheel, .arbors projecting from the work carrying plate in circumscribing relation to the friction drivewheel, the friction drive wheel andvarbors being rotatable at slower speeds than .the grinding wheel and about axes eccentric to .one another whereby Work pieces carried `by the arbors are brought into simultaneous engagementwith the grinding wheel and friction drive wheel when within the grinding throat, means for rotating the work carrying .plate at a slower speed than *the rotation of` the -friction .drive wheel, means disposed radially `of the friction drive wheel and Work carrying plateffor positive engagement with the work for actuating same relative to the ar- Vboris and positioning the work thereon, means for positively actuating said work positioning means, additional means extending radially of the friction drive wheel vand work carrying plate :for ejecting the work from the arbor at the conclusion of the grinding operation, said ejecting -means comprising friction rollers disposed at a distance from the arbors substantially equal to the wall thickness of the work and engaging the work between the said rollers and the adjacent surface of the arbors, and means for adjusting the position -of the rollers relative to the arbors to enable `different sizes of work pieces to be ground.

A 6. Ar work presentation mechanism for use with grindingr machines comprising a rotatable work carrying plate,v a bearing therefor, work Ysupports projecting from the plate and adapted feeding the work past the -grindingwheeLarbors I 7. A vwork presentation mechanism `fer 5 f with grinding `machines comprisingja rotatable work carrying plate, a bear-ing therefor, -work supports projecting 'fromthe plate and adapted Y -to enter the bore in work pieces, a frictiomdrive wheel disposed beneath thelsupports and f tric. thereto for engagement with the worknd effecting its rotation at -a definite point fin its' `Ycycle of movement, means for engagement'yith the work for positioning-,it relativefto thelsgpport, additional means for ejecting vthe work from Y Athe support at the conclusionof the Y, 1

operation, said vpositioning and 'ejecting Y each comprising rotatable yrollers, rotatinginfopposite'directions for reversely actuating thework A Vpieces relativeto the supports, and ,means vier adjusting the positions-of the rollers y the work supports for various sizes of workpiece; said adjustable means comprising 'akhousng each rollerand a coupling between the housings :Si

of` the positioning rollers Y, and Yejecting uollalfsv whereby they may be adjustedV one Awithrespect f to the other to thereby, adjusttheunits :individually.` l

8. lin Va grinding machine the combination with y afbed and aigrinding'wheel rotatably-mounted thereon, of a work presentation `and feeding unit comprising a housing mounted on the bed, :a spindle `rotatably journaled therein, la, friction drive wheelnsecured to the spindle -or rotation, therewith, a Awork actuating `carrier mojmtedjm the bed adjacent the friction drive wheelA far projecting` from the carrier inv overlying relation to the friction drive wheel and circrumiinib, ing same, means for rotating the friction Wheel and carrier at differential rates Awhich'aa'eY slower than the rate of rotation-of the :grindingV wheel, positivemeans for positioning theimk on the .arbors,' and additional positive' means for ej ecting the work from the arbors, said means im' `rotating the carrier includinga Vprime ritenuta',Y e j 'worm and worm wheel for rotating the fcarrlq', a transmission' 'betweenl the.' prime mover :and worm ,and worm' wheel, andanadditional transmission Ifromfthe-worm wheel drive `to thexnposltive workpositioning and ejectingrmeans Y 9. A work supporting and feedinggmechanism for use'with .a grinding machine comprising a rotatable carrier, aplurality of arbors projecting therefrom each adapted to be receivedin thehun of a work piece, means for rotating 'the'.carrierto cause the arbors to present :the work'can'led thereby to the grinding wheel, and* means disposed radially of the carrier for engagement. with the work while on the arbors' for positioning -said work relative to thearbors priorxto the g `engagement thereof with the grindinglwheel; i, for. ejecting saidwork from the rarborsr atterrit has passed the grinding wheel, said positioningk and ejecting meanscomprising a .plurality of rollers each4 having their periphery spaced from the j arbors a distance slightly less than the of the work, and means for rotating 4the positioning rollers in one direction and the ejecting'roller's inthe reverse'direction.v Y v v j 10.V A work supporting'and feeding mechanism for use Ywithv a'grinding" machine comprising a rotatable carrier, a' plurality ofv arbor's projecting therefrom each adapted to be-receivedin thebore of' a wor-k piece, means Afor rotating 'u rer to cause the arbors to present the work carried thereby to the grinding wheel, and means disposed radially of the carrier for engagement with the work while on the arbors for positioning said work relative to the arbors prior-to the engagement thereof with the grinding wheel and for ejecting said work from the arbors after it has passed the grinding wheel, said means comprising rollers spaced from the arbors a distance equal to the thickness of the work, a housing for said rollers, means supporting said housing for adjustment toward and from the arbors, and additional means supporting said rollers for adjustment relative to one another independent of the housing adjustment to vary the capacity of the device. l

11. In a grinding machine for grinding the exterior surface of cylindrical fragile sleeves and the like the combination of a bed, a pair of opposed grinding and friction drive wheels on the bed and forming between them a grinding throat, a work arbor adapted to enter the bore in the sleeves for passing the same through the grinding'throat, and means on one side of the arbor for engaging the wall of the sleeve between itself and the arbor for positioning saidjsleeve on the arbor.'

12. In a grinding machine for grinding the exterior surface of cylindrical fragile sleeves andthe like the combination of a bed, a pair of opposed grindingV and friction drive wheels on the bed and forming between them la grinding throat, a work arbor adapted to enter the bore in the sleeves Vfor passing the same through the grinding throat, means on one side of the arbor for engaging the wall of the sleeve between itself and the arbor for positioning said sleeve on the arbor, and additional means'on one side of the arbor for engaging the wall of the sleeve between itself and the arbor for ejecting the work piece from the arbor. Y

13. In a grinding machine of the class described for grinding the outer wall of cylindrical fragile sleeves and the like the combination of a bed, a pair of opposed grinding and friction drive wheels forming between them a grinding throat of a size substantially equal to the final size of the work piece, an arbor adapted to enter the bore through the sleeve, means for actuating the arbor through the grinding throat, and means at one end of the throat for engaging the sleeve between itself and the arbor for forcing the sleeveV onto the arbor prior to the movement of the arbor and sleeve through the grinding throat.

14. In a grinding machine of the class described for grinding'the outer wall of cylindrical fragile sleeves and the like the combinationof a bed, a pair of opposed grinding and frictionV drive wheels forming between them a grinding throat of .a size substantially equal to the final size of the work piece, an arbor adapted to enter the bore through the sleeve, means for actuating the arbor through the grinding throat, means at one sleeves and the like the combination of a bed,V

a Vpair of opposed grinding and friction drive wheels forming between them a grinding throat of a size substantially equal tothe final size of the work piece, an arbor adapted to enter the bore through the sleeve, means'for actuating the arbor through the grinding throat, means at one end of the throat for engaging the sleeve between itself and the arbor for forcing the sleeve onto the arbor prior to the movement of the arbor and sleeve Vthrough Vthe grinding throat, and means on the other end of the grinding throat for engagingv the sleeve between itself and the arbor and ejecting the sleeve from the arbor, each of said last two named means including a `rotatable roller having their axes skewed with respect to the arbor axis.

16. A work presentation mechanism for presenting hollow fragile Work pieces to the action of a grinding Wheel comprising a rotatable work carrying plate, a bearing therefor, work supports projecting from the plate and adapted each to enter the bore in a work piece, means eccentric to the plate supports for engaging the wall of the Work piece between itself and each ofthe work supports for forcing the said work pieces individually on its support, and additional means eccentric to the work supports for again engaging between itself and the said supports the wall of the workpiece for forcing said work pieces from their supports. l Y 17. A work presentation mechanism for presenting hollow fragile Work pieces to the action of a grinding Wheel comprising a rotatable work carrying plate, a bearing therefor, work supports projecting from the plate and adapted each to enter the bore-in a work piece, means eccentric to thew plate supports for engaging the wall of the work piece between itself and each of the work supports for forcing the same work pieces individually on its support, additional means eccentric to the work supports for again engaging between itself and the said supports the wall of the workpiece for forcing said work pieces from their supports, said last two mentioned means each including a roller having their respective axesY angularly related to one another and angularly relatedin opposite directions to the axis of the supports, and means for rotating said rollers about their respective axes for thereby shifting the work pieces onto and off of the said supports.

FREDERICK J. THELER. 

